1.

Solve for x and y:\(\frac{3}{x+y}+\frac{2}{x-y}=2\),\(\frac{9}{x+y}+\frac{4}{x-y}=1\)

Answer»

The given equations are

 \(\frac{3}{x+y}+\frac{2}{x-y}=2\)....(i)

\(\frac{9}{x+y}+\frac{4}{x-y}=1\)......(ii)

Substituting 1/x+y = u and 1/x−y = v, we get: 

3u + 2v = 2 ……..(iii) 

9u - 4v = 1 …….(iv) 

On multiplying (iii) by 2, we get: 

6u + 4v = 4 …..(v) 

On adding (iv) and (v), we get: 

15u = 5 

⇒u = 5/15 = 1/3 

⇒ 1/x+y = 1/3 

⇒ x + y = 3 …….(vi) 

On substituting u = 1/3 in (iii), we get 

1 + 2v = 2 

⇒2v = 1 

⇒v = 1/2 

⇒ 1/x−y = 1/2 ⇒ x – y = 2 …….(vii) 

On adding (vi) and (vii), we get 

2x = 5

⇒ x = 5/2 

On substituting x = 5/2 in (vi), we have 

5/2 + y = 3

⇒ y = \((3-\frac{5}2)\)= 1/2 

Hence, the required solution is x = 5/2 and y = 1/2 .



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